What college courses should I take if I want to be a video game designer, writer, artist, or QA tester?

Each of the disciplines you listed require a more specific subset of courses. For QA tester knowledge of a program like java for help creating things is good, but if you want to automate processes then python is a better choice. Knowing a query language such as SQL is also quite useful. This would be a good starting point, you can always learn other languages from here since the majority of them follow the similar rules or structures. For artists usually the best thing you can do is figure out what kind of art? Illustration? Concept? User interface? Figuring out what art and medium you want to focus on goes a long way. If you like working photoshop focus on digital design, but if you like working with acrylic paint or charcoal then go with something else. Narrow down your focus and you will have the most success.

As mentioned above, Graphic Design is an excellence choice to learn about. Using visuals for communication is very powerful.

I echo the recommendation for Public Speaking as well. Learn about pursuading people and making your point clearly and concisely through verbal communication. This can also build confidence.

Courses on technical writing (non-fiction writing in general) will also help with communication. Being able to communicate your ideas improves the chances of them being implemented.

There are also entire college degrees in video games. Consider going to a college that specializes in this field to get a wide gamut of applicable courses. (Vancouver Film School, Digipen, etc.)

It sounds like you have games you want to make and stories you want to tell. The best advice I can give you is to make games. Once you actually make a game from start to finish, you'll get a better idea of what's involved and why games are done a certain way. I suggest you start very simple. Think of a simple story you want to tell and a simple game mechanic and find an easy game engine (like Unity) to make it in. Or find a group of people who are already doing that same thing. That will give you an idea of what it takes to make a game. Once you get into it, you'll find there are some parts of the game development you enjoy working on more than others. Games are made by a large group of individuals with varying specialties - game designers, artists, engineers, producers, managers, analysts, quality assurance, etc. All of those people contribute to the design, story, and look/feel of the game in different ways. So any one of those positions might be the best job ever for you, but you won't know until you try. :) Also find a way to visit a game company!

I would say some courses on the technical side would be:

Programming (particulatly languages used in whatever type of games you'd like to design)
Graphic design
Logic
Also, look at the ISTQB certification for testing especially

For the development side some things would be:

Business management/administration
Public Speaking

Also, its always a good idea to intern in the area you want. You get experience and you get to really see the day to day of the job. Sometimes jobs don't live up to what you imagined. Sometimes they are more than you imagined.